Method and a system for wrapping objects and use of the method

ABSTRACT

The invention involves a method and a system and use of the method for wrapping one or more objects ( 6 ) in stretch film, said film ( 1 ) comprising a tube-like section, the diameter of which is smaller than the diameter of the object or objects to be wrapped, said film comprising a first end ( 2 ) and a second opposite end ( 4 ), wherein the film is opened at its first end and provided with a number of folds transversally of its longitudinal axis, following which the film is expanded diametrically. Novel aspects comprise that the object or objects are supported and advanced essentially horizontally or under a flat angle in relation to the horizontal into the expanded film from the first free end thereof towards the second end of the film, which other end is closed, following which the film is pulled around the object or objects the folds of the film being unfolded, until the entire object or objects is/are introduced into the film, following which the first end of the film is closed by joining for complete enclosure of the object or objects in the film. Hereby, compared to the prior art, it is accomplished that the object or objects is/are enclosed on all sides and hence completely.

The invention relates to a method of wrapping one or more objects instretch film, said film comprising a tube-like section, whose diameteris smaller than the diameter of the object or objects to be wrapped,said film comprising a first end and a second opposite and closed end,where the film is opened at its first end and provided with a number offolds transversally of its longitudinal axis, following which the filmis expanded diametrically before being brought to enclose the object orobjects. The invention also relates to a system of carrying out themethod, wherein one or more objects is/are wrapped in a tube-likesection of stretch film, said film comprising a tube-like section, whosedimension is smaller than the dimension of the object or objects to bewrapped, said film comprising a first end and a second opposite andclosed end; wherein the system comprises means for opening the film atits first end and means for moving the film across a hollow stretchingunit and providing the film with a number of folds transversally of itslongitudinal axis, said stretching unit comprising means for expandingthe film diametrically and means for forming holding-back means duringrelease of the film. Moreover, the invention relates to a use of themethod.

It is already known to wrap objects in stretch film. U.S. Pat. No.4,050,219, DE 2,706,955, DE 3101310 and EP 0 344 815 A1, incorporatedhereby by reference, teach processes, wherein a tubular film havingsmaller circumferential dimension that the object to be wrapped isshifted down over and arranged in folds on a stretching unit, followingwhich the end of the film is closed by welding, whereby a bag is formedwhose bottom faces upwards. The film is subsequently expandedhorizontally and pulled vertically down over a number of items stackedon a pallet. In proximity of or underneath the pallet the film is letgo. By this wrapping the items are stabilised on the pallet, the filmremaining, following application, to a certain extent tensioned, andlikewise a certain degree of coverage and protection are also impartedto the items.

The thus known processes for wrapping are associated with the exemplaryweakness that the side facing towards the pallet remains unprotected. Itfollows that the objects are not fully wrapped and are therefore able toabsorb moisture, smell and the like. The objects being arranged on thepallet, which is in turn sitting on a support, it is not possible toconvey the film underneath the pallet and close it off completely. It isa further aspect that the processes are not suitable for objects thatare not arranged on a pallet or some other carrier means. Theunderside(s) of the lowermost object(s) will thus be fully exposed.Moreover there is a risk of the objects falling out of the wrapping frombelow.

Novel aspects of the method according to the invention comprise that theobject or objects are supported and advanced essentially horizontally orunder a flat angle relative to the horizontal into the expanded filmfrom its first open end towards the second end of the film, followingwhich the film is pulled around the object or objects, the folds of thefilm being unfolded until the entire object or objects are introducedinto the film, following which the first end of the film is closed byjoining for complete enclosure of the object or objects in the film.

Hereby, compared to the prior art, it is accomplished that the object orobjects are enclosed to all sides and hence completely. Thereby it isalso accomplished that the objects need not be arranged on a pallet orthe like to avoid contact with a support on which the wrapped object(s)is/are arranged.

According to a preferred embodiment the film may, during advancement ofthe object or objects within the film, be arranged at a space between afirst and a second support, where the object or objects is/are, duringthe advancement, moved from the first to the second support. In thismanner the object or objects may remain essentially supported during theentire movement, including in particular if the objects are longcompared to the expanse of the space.

According to an alternative embodiment the object or objects can bearranged on the first support and seized with seizing means, followingwhich the object or objects are introduced into the film and arranged onthe second support, following which the object or objects is/are let go.

According to yet an embodiment at least the first support may comprisemeans for displacing the object or objects. This is advantageous as theobject or objects are to be moved from the first to the second support.Thus, the means for displacement need only eg push the object orobjects.

According to a preferred embodiment the first support may bedisplaceable or comprise a displaceable section, wherein the firstsupport or section is displaced and introduced into the expanded filmfor further support of the object or objects during movement from thefirst to the second support. Thereby the object or objects can besupported during a larger part of the movement between the first and thesecond support. That may be advantageous when relatively short objectsare wrapped.

According to yet a preferred embodiment the film may be tensioned fortightening when being pulled around the object or objects. Hereby lessfilm is used and, likewise, the film becomes tidy and smooth. When anumber of objects are wrapped simultaneously, the film will also supportthe objects. If the load is increased and imparts a permanent increasein length to the film, further film savings are obtained and thesupporting effect is enhanced. It is also obtained that objects having atendency to shrink will remain tightly wrapped and hence stable as thefilm will follow the shrinkage due to its tensioning.

According to yet a preferred embodiment the first, the second and thefurther support may be roller paths and/or conveyor belts. This enableseasy incorporation of the method in connection with production plantswhere the objects are transported by those types of transporter means.

Joining may advantageously be accomplished by welding which yields aquick and reliable result.

According to yet an embodiment the object or objects may be arranged ona carrier means such as a pallet. It may be practical in case of stackedobjects or objects that are otherwise difficult to move.

The film may be dispensed from a storage unit from where it is cut to asuitable length and closed at its other end by joining prior to folding.Thereby the film may be eg in roller shape, which saves place. Otherwisepieces of film manufactured in advance can be used, that have alreadybeen shortened and closed at the one end.

The film on the storage unit can be provided with longitudinallyextending folds that reduce the width of the film. Thereby weldinggussets used for joining the film need not be so wide.

Novel aspects of the system according to the invention comprise that thesystem comprises means for supporting and advancing, essentiallyhorizontally or at a flat angle in relation to the horizontal, theobject or objects through the stretching unit with the film in expandedstate for pulling of the film around the object or objects and completeintroduction of it or them into the film and means for closing orjoining the first end of the film for complete enclosure of the objector objects in the film.

According to a preferred embodiment the system may comprise a firstroller path from where the object or objects is/are advanced to thestretching unit, a displaceable roller path section that can bedisplaced into the stretching unit when the latter has expended the filmand a second roller path for receiving the object or objects. Therebythe system is readily integrated into production plants where objectsare transported in a similar manner. By the displaceable roller pathsection the object or objects are supported to a large extent.

According to a preferred embodiment the system may comprise means fordispensing film from a storage unit.

According to a further preferred embodiment the system may also comprisemeans for welding and means for cutting off the film, which means aredisplaceable and arranged after the stretching unit.

According to yet an embodiment the stretching unit may comprise operatedrollers for winding film, which rollers will, during pulling of the filmaround the object or objects, form holding-back means. Also the rollersmay contain means measuring the angulation, including encoders, wherebyit is possible to measure and control how much film is introduced ontothe stretching unit.

Novel aspects of the use of the method comprise that one or more objectsare wrapped, which objects are essentially flat and elongate, andwherein the object or objects are wrapped with the longitudinal axissituated in parallel with an axis extending between the first and thesecond ends of the film,

In the following the invention will be described in further detail withreference to figures that illustrate examples of embodiments of theinvention. The technique is given in a simplified manner to emphasizethe novel aspects of the invention. Other structural details will beknown to the person skilled in the art and will appear ia from U.S. Pat.No. 4,050,219, DE 2706955, DE 3101310 and EP 344815 A1 incorporatedherein by the present reference.

FIGS. 1-5 show schematic cross-sections of a system according to oneembodiment of the invention. The figures teach ia an example of awrapping procedure;

FIGS. 6-7 teach schematic cross-sections of a system according to analternative embodiment of the invention.

FIGS. 1-7 show a number of objects 6 that are to be wrapped in a tubularfilm 1. Also one single object 6 may be wrapped and, likewise, two ormore objects, including stacked objects and objects arranged on acarrier means, may be wrapped. Preferably the film 1 has an expansewhich is smaller than the expanse of the objects 6. The figures show aframe structure 26 that carries the various components, includingmiscellaneous guide means, etc, that partake albeit they are not shown;that may, however, readily be exercised by the person skilled in the artas they present common knowledge within the prior art wrappingtechniques and appear from the above-referenced respective documents.

FIG. 1 shows the film 1 that is dispensed from a storage unit 8, fromwhere it is conveyed to a distributor head 22 that is, by means of asuction discs, able to open the film 1 at the first end 2 thereof, whenthe latter is to be conveyed onto a stretching unit 10. The distributorhead 22 is movable and comprises means for conveyance of the opened film1 into or across the stretching unit 10. On the stretching unit 10 thefilm 1 is arranged in a number of folds to occupy as much space aspossible in the horizontal direction. To assist movement of the film 1the stretching unit may comprise operated rollers 20, which rollers mayalso form holding-back means when the film 1 is to be applied to theobject or objects 6 when the film 1 is pulled off the stretching unit10.

In FIGS. 1-5 a first roller path 12 is shown that has a displaceableroller path section 15, and a second roller path 14. Roller paths aresuitable for use in connection with the wrapping, but conveyor belts arealso suitable. The roller paths 12 and 14 can be completely or partiallyoperated. If the roller path 12 is not operated, the objects 6 can bepushed, eg by means of a pneumatic cylinder to produce a desiredmovement. Moreover, FIGS. 1-5 also show means for welding 16 and meansfor cutting 18.

In FIG. 2 a suitable length of film 1 is arranged on the stretching unit10, and means for welding 16 join the film 1, following which means forcutting 18 separate the piece of film on the stretching unit 10 from theremainder of the film.

FIG. 3 shows that the distributor head 22 is displaced upwards in orderfor it to be clear of the path of the objects 6 during the wrapping, butit may just as well be displaced sideways. Means for welding 16 are alsotaken it clear positions. By joining, see FIG. 2, the clear film on thestretching unit is provided with a closed end 4, following which thefilm is expanded by the stretching unit. During application of the filmon the stretching unit, it is pulled together, whereby the film iseasily displaced there across. By the expansion the circumferentialdimension of the film becomes diametrically larger than the objects 6.The displaceable roller path section 15 is displaced into the stretchingunit 10 and into the expanded film. Between the roller path 12 (and thesection 15) and the roller path 14 a space 24 is provided that allowsthe film to come from the underside of the roller path section 15 and upon the top face of the roller path 14.

FIG. 4 shows how the film 1 is pulled off the stretching unit 10 andpulled around the objects 6. The rollers 20 form holding-back meanswhereby the film 1 is stretched suitably and preferably tensioned to theeffect that it is situated tightly longitudinally of the objects.Holding-back means can be accomplished in other ways without use ofrollers, eg with a fixed back edge that yields frictional resistance:The film 1 may also be pulled with more tension, whereby a permanentincrease in length is imparted thereto. When the film 1 is pulled aroundthe objects 6, the film maintains a certain tensioning whereby theobjects are stabilised. A part of the tensioning compresses the stack ofobjects 6 and thereby follows the objects should they settle duringtransport or storage and, likewise, the pressure presses the objectstowards each other and hence creates mutual friction that furthercontributes to stabilisation.

In FIG. 5 the objects 6 have been conveyed entirely into the film, andthe first end 2 has been closed by joining by means for welding 16. Thismay be controlled in that—immediately preceding release of the end 2 ofthe film from the rollers 20—means for welding 16 are conveyed towardseach other and join the film. If necessary, excessive film 1 can be cutoff. Prior to joining the roller path section 15 can be withdrawn andthe stretching unit be pulled together, and likewise the film can bereleased from the rollers 20 to thereby minimise the amount of excessivefilm following the joining. It is noted that the same means for welding16 can be used for joining both the first end 1 and the second end 4 ofthe film 1. The objects 6 are now completely wrapped. When the objects 6have been removed, the roller path section 15 can be withdrawn, thestretching unit 10 pulled together, and the distributor head 22 can belowered down in front of the stretching unit, whereby the system is backto its starting situation, see FIG. 1, and renewed wrapping can becommenced.

FIG. 6 shows an alternative embodiment wherein a stretching unit 10 isapplied with film 1 corresponding to FIG. 1, but with the differencethat the stretching unit 10 can be moved vertically and as shownreceives the film 1 in a raised position. Hereby improved space isaccomplished around the stretching unit 10 for miscellaneous functionalmeans, whereby the film 1 is more readily applied to the stretchingunit. Thus, the distributor head 22 can be stationary, while means 16for welding the film 1 for forming a closed end 4 are verticallymovable, and including also adaptation for closure of the open end 2 ofthe film following wrapping of an object. FIG. 7 shows the stretchingunit 10 in a lowered position, which corresponds to the situation shownin FIG. 2. Now the film 1 must be expanded by the stretching unit 10,corresponding to FIG. 3, following which the wrapping can beimplemented, see FIGS. 3, 4 and 5. In this context, too, the verticallymovable means 16 for welding are configured to close the end 2 of thefilm 1, whereby complete wrapping is accomplished.

The figures show the use of roller paths, but movement of the object orobjects 6 can be accomplished in numerous ways. All it takes are twosupports (locations), between which the expanded film 1 is arranged.Then the objects 6 can be moved, eg pushed by means of piston, from thefirst to the second support, eg sliding on the supports. Also theobjects 6 can be seized with seizing means, eg configured as a settweezers or a claw or be taken by means of forks like the forks of aforklift truck and conveyed from one support to the other. Thefundamental principle is that the objects 6 are conveyed, while beingsupported, into the expanded film 6, where the latter is pulled aroundthe objects 6. Depending on the length and rigidity (and nature ingeneral) of the objects 6, the supports may be arranged with a givenspace there between without tilting downwards. If that is a problem, adisplaceable support or part of the support, eg like a tongue, isconveyed to a position to minimize said space.

Objects 6 may be of different lengths and yet be wrapped with the samefilm and stretching unit 10. The length may be controlled by measuringhow much film 1 is arranged on the stretching unit. It can beaccomplished ia by providing the rollers 20 with encoders.

It will be understood that the invention as described in the presentdescription and figures can be modified or changed and continue to becomprised by the scope of protection of the patent claims that follow.

1. A method of wrapping one or more objects (6) in stretch film, whichfilm (1) comprises a tube-like section, the diameter of which is smallerthan the diameter of the object or objects (6) to be wrapped, which film(1) comprises a first end (2) and a second opposite and closed end (4),wherein the film (1) is opened at its first end (2) and provided with anumber of folds transversally of its longitudinal axis, following whichthe film (1) is expanded diametrically, wherein the object or objects(6) is/are conveyed by roller paths and/or conveyor belts (12, 14),essentially horizontally or under a flat angle in relation to thehorizontal, into the expanded film (2) from its first end (2) towardsthe second end (4) of the film, following which the film (1) is pulledaround the object or objects (6) as the folds of the film are unfolded,until the entire object or objects (6) have been introduced into thefilm (1), following which the first end (2) of the film is closed byjoining for complete enclosure of the object or objects in the film,characterized in that the film (1) is, during advancement of the objector objects (6) in the film, arranged at a space between the first (12)and the second (14) roller paths and/or conveyor belts, and wherein theobject or objects are conveyed from the first (12) to the second (14)roller paths and/or conveyor belts.
 2. A method according to claim 1,characterized in that the object or objects (6) are arranged on thefirst roller paths and/or conveyor belts (12) and seized by seizingmeans, following which the object or objects are introduced into thefilm (1) and arranged on the other roller paths and/or conveyor belts(14), following which the object or objects are let go.
 3. A methodaccording to claim 1, characterized in that the first roller pathsand/or conveyor belts (12) is displaceable or comprises a displaceablesection (15), wherein the first roller paths and/or conveyor belts (12)or section (15) is displaced and introduced into the expanded film (1)for further supporting the object or the objects (6) during movementfrom the first (12) to the second (14) roller paths and/or conveyorbelts.
 4. A method according to claim 1, characterized in that the film(1) is tensioned for tightening when being pulled around the object orobjects (6).
 5. A method according to claim 4, characterized in that thetensioning imparts a permanent increase in length to the film (1).
 6. Amethod according to claim 3, characterized in that the section (15)comprises roller paths and/or conveyor belts.
 7. A method according toclaim 1, characterized in that the joining is accomplished by welding.8. A method according to claim 1, characterized in that the object orobjects (6) are arranged on a carrier means such as a pallet.
 9. Amethod according to claim 1, characterized in that the film (1) isdispensed from a storage unit (8), from where it is cut to a suitablelength and closed at its second end (4) by joining prior to folding. 10.A method according to claim 9, characterized in that the film (1) on thestorage unit (8) is provided with longitudinally extending folds thatreduce the width of the film.
 11. A system of exercising the methodaccording claim 1, wherein one or more of the objects (6) are wrapped instretch film, said film (1) comprising a tube-like section, the diameterof which is smaller than the diameter of the object or objects (6) to bewrapped, which film (1) comprises a first end (2) and an opposite andclosed end (4), wherein the system comprises means for opening (22) thefilm at its first end and means for moving (20, 22) the film across ahollow stretching unit (10) and providing the film with a number offolds transversally of its longitudinal axis, said stretching unit (10)comprising means for expanding the film diametrically and means forforming holding-back means (20) while the film is being released,wherein the system comprises roller paths and/or conveyor belts (12, 14)for conveying, essentially horizontally or under a flat angle inrelation to the horizontal, the object or objects (6) through thestretching unit (10) with the film (1) in expanded state for pulling thefilm (1) around the object or objects (6) and completely introducing itor them into the film (1), and means for closing and joining (16) thefirst end (2) of the film for complete enclosure of the object orobjects (6) in the film characterized in that said roller paths and/orconveyor belts (12, 14) comprise a first (12) and a second (14) rollerpaths and/or conveyor belts, wherein the film (1), during the conveyingof the object or objects (6) in the film, is arranged at a space betweensaid first and a second roller paths and/or conveyor belts (12, 14), andwherein the object or objects are conveyed from the first (12) to thesecond (14) support.
 12. A system according to claim 11, characterizedin that the first support (12) is displaceable or comprises adisplaceable section (15), wherein the first support (12) or section(15) is displaced and introduced into the expanded film (1) for furthersupporting the object or the objects (6) during the conveying from thefirst (12) to the second support (14).
 13. A system according to claim11, characterized in that said displaceable section (15) comprisesroller paths and/or conveyor belts.
 14. A system according to claim 11,characterized in that the system comprises means for dispensing filmfrom a storage unit (8).
 15. A system according to claim 11,characterized in that the system comprises means for welding (16) andmeans for cutting off (18) the film, said means being displaceable andarranged after the stretching unit (10).
 16. A system according to claim11, characterized in that the stretching unit (10) comprises operatedrollers (20) for winding of film (1), said rollers forming holding-backmeans when film is pulled around the object or objects (6).
 17. A systemaccording to claim 16, characterized in that the rollers (20) comprisemeans for measuring angulation, including encoders.
 18. The methodaccording to claim 1, wherein said objects (6) are essentially flat andelongate, and wherein the object or objects (6) are wrapped with thelongitudinal axis situated in parallel with an axis extending betweenthe first end and the second end (2, 4) of the film.
 19. The systemaccording to claim 11 wherein said objects (6) are essentially flat andelongate, and wherein the object or objects (6) are wrapped with thelongitudinal axis situated in parallel with an axis extending betweenthe first end and the second end (2, 4) of the film.